The present invention relates to a support ring for use in the surgical correction of heart valve disorders.
A human heart generally includes four valves. One of these valves, the mitral valve, is located in the left atrioventricular opening and serves to prevent back flow, or regurgitation, of blood being pumped through the heart. Regurgitation can reduce cardiac output and cause other cardiac problems. Various diseases and natural defects can cause a valve to fail to operate properly and regurgitate. Dilation or deformation of the mitral valve annulus can cause regurgitation. One method of eliminating or reducing regurgitation is restoring the proper size and shape of the valve annulus in a procedure known as annuloplasty.
Annuloplasty involves the surgical implantation of a support ring about the dilated valve annulus, in this case the mitral valve annulus, restoring the natural size and shape to the annulus and allowing the valve leaflets to function normally. Since the annuloplasty technique was first implemented, several designs of the annuloplasty ring have been developed. In one of the earliest designs, a rigid ring was sewn about the valve annulus, see e.g., U.S. Pat. No. 3,656,185. Rigid rings serve the basic purpose of restoring the valve annulus to its natural shape. However, rigid rings can have several negative effects, including restricted contraction of the left ventricle.
Another annuloplasty ring design is a fully flexible ring, see e.g., U.S. Pat. No. 4,061,277. The fully flexible ring has the advantage of allowing a more normal three-dimensional movement of the tissue surrounding the valve annulus. However, a fully flexible ring generally is not able to restore the natural shape of the valve annulus and tends to be more difficult to implant. Additional annuloplasty ring designs include various partial rigid rings and rings with rigid and flexible portions, see e.g., U.S. Pat. No. 5,061,277.
Many of the partial rings and rigid/flexible rings are designed so that the rigid portion is sutured adjacent the anterior portion of the mitral valve annulus, while the posterior portion of the mitral valve annulus has no support or a flexible support. These designs tend to create the same problem known as systolic anterior motion (SAM), where the anterior leaflet of the mitral valve bulges out into the left ventricular out flow track (LVOT) causing obstruction of the blood flow into the aortic valve. Another partial ring is designed so that the partial, rigid ring is sutured adjacent the posterior portion of the valve annulus. However, when the posterior portion of the valve annulus is supported and the anterior portion has no support, the anterior portion may dilate or deform.
Therefore, there is a need for an annuloplasty ring that is easily implantable, restores the valve annulus to its natural shape, and does not induce systolic anterior motion.